Possible mechanisms of control of gene expression for the onco-developmental serum protein, alpha-fetoprotein (AFP), will be explored. Alpha-fetoprotein production by liver cells is affected by a number of regulatory factors. These include growth states of normal hepatocytes in vitro and in vivo; as well as hepatocarcinogen exposures; exposure to chemicals, such as phenobarbitol, that modify cellular metabolism; hormonal stimulation; and growth of hepatocellular and endodermal sinus (yolk sac) tumors. These factors may operate at different levels in controlling AFP production. We intend to focus on two levels of control, 1) identification by immunochemical methods of non-histone proteins that may be specifically associated with AFP production and 2) measurement of mRNAAFP by translational activity and cDNA probes. These studies should not only provide significant insights into the relationship of AFP production to carcinogenesis, but also provide basic information on gene control mechanisms of eukaryotic cells.